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OMIG Main Page | 2005 Abstracts | < Previous | Next > 0.005% Benzalkonium Chloride (BAK): Is it Effective in Eliminating Staphylococcus aureus and Pseudomonas aeruginosa? R.P. Kowalski, B.R. Kowalski, P.P. Thompson, E.G. Romanowski, F.S. Mah, Y.J. Gordon. The Charles T. Campbell Laboratory, University of Pittsburgh, Pittsburgh, PA Purpose. We determined the in vitro efficacy of 0.005% BAK as a biocide alone, and with moxifloxacin (MOX) and gatifloxacin (GAT) to eliminate Staphylococus aureus and Pseudomonas aeruginosa. Methods. Standard time-kill studies were determined with 5 isolates each of Staphylococcus aureus and Pseudomonas aeruginosa. Bacteria survival was tested at hours 1, 2, 4, 6, 8 and 24 hours to: 1) vehicle (Mueller Hinton broth), 2) 0.005% [50 ug/ml] BAK, 3) 0.5% MOX, 4) 0.3% GAT, 5) 0.3% GAT + 0.005% BAK, and-6) 0.5% MOX + 0.005% BAK. The initial inoculum was 1 x 106 cm/ml. The MICs of all the isolates were determined to BAK using the broth dilution method. Results. For Staphylococcus aureus, 0.005% BAK, 0.3 % GAT + 0.005% BAK, and 0.5% MOX + 0.005% BAK eliminated all growth within 1 hour. 0.3% GAT + 0.005% BAK (median 1 hr) eliminated bacteria faster than 0.5% MOX (median 4 hrs) (p=0.016). The MICs to BAK ranged from 1 to 8 ug/ml. For Pseudomonas aeruginosa, 0.005% BAK had no eliminating effect. 0.3% GAT, 0.5% MOX, 0.3% GAT + 0.005% BAK, and 0.5% MOX + 0.005% BAK eliminated all growth within 1 hour. The MICs to BAK ranged from 64 to >128 ug/ml. Conclusions. 0.005% BAK appears to complement GAT for eliminating Staphylococcus aureus while it has no effect on Pseudomonas aeruginosa. GAT and MOX appear to act as self-preservatives against P. aeruginosa. It is possible that BAK (depending on concentration) may not preserve all topical ocular non-antibiotic medications against P. aeruginosa. Disclosure code: N OMIG Main Page | 2005 Abstracts | < Previous | Next >
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